Getting Absolute Area of Multiple Models

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#1

hey there devs.

I have been working on a sandbox railway system which generates the rails with an algorithm, forming the rail piece with multiple smaller segments. What i want to do is be able to generate a part that will contain a SelectionBox that covers the area of the rail piece.

The smaller rail segments that make up the larger rail are stored as models in a folder. I’m not sure if i could use a model instead, and use a function built-in to models to get the absolute area of the model, or that doesn’t exist, and i need to use a more complex algorithm to calculate it.

here is an example of what i mean, but with the SelectionBox part hand-built:

image
image644×592 339 KB

Thankyou for any help,

  • Mezza
#2

I’d look into model:GetBoundingBox() it returns the cframe orientation along with a vector3 size Model | Documentation - Roblox Creator Hub

#3

Thus, to create a box to cover that segment

local function createSelection(model)
    local orientation, size = model:GetBoundingBox()
    local p = Instance.new("Part")
    p.Anchored = true
    p.CFrame = orientation
    p.Size = size
    p.CanCollide = false
    p.Transparency = 1
    local s = Instance.new("SelectionBox")
    s.Adornee = p
    s.Color3 = Color3.fromRGB(255, 255, 255)
    s.Parent = p
    p.Parent = workspace -- or where ever you want it placed.
end

this was un-tested and wrote in the forum reply, but hopefully it helps.

#4

Thank you. Yeah, your code is pretty much what i came up with. :+1:

#5

I’ve run into a problem. For some reason, every model’s generated part has one of its corners at Vector3(0,0,0). Is this something wrong with my implementation?

local htbx = Instance.new("Part", trckp)
local o, s = trckp:GetBoundingBox()
htbx.Name = "Hitbox"
htbx.Anchored = true
htbx.Size = s
htbx.CFrame = o
htbx.TopSurface = Enum.SurfaceType.Smooth
htbx.BottomSurface = Enum.SurfaceType.Smooth
htbx.Transparency = 1
htbx.CanCollide = false

local slcb = Instance.new("SelectionBox", htbx)
slcb.Visible = false
slcb.Adornee = htbx
slcb.Color3 = Color3.fromRGB(134, 134, 134)
#6

Honestly I don’t see anything wrong with your implementation, but I would like to make note that assigning a parent with-in the Instance.new() can mess with performance if you’re messing with properties afterwards.

#7

Ok thanks for letting me know that. Its wierd, one of the corners is always at 0,0,0 even though i checked that all the parts and models are in the right spot

#8

Ok, it seems as though changing what you said about parent assignment in Instance.new actually fixed the problem, odd.

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#9

That’s good to know, glad it helped.

1 Like